01:119:116 Lecture Notes - Lecture 7: Agnatha, Amniote, Symmetry In Biology
25 Jul 2017
School
Department
Course
Professor
Document Summary
Blastopore becomes anus (remember: other organisms do this convergent evolution) Ca of deuterostomia had these traits, but other organisms have them too by convergence. Sea stars, sea urchins, sand dollars, sea cucumbers. Adults often have 5-part symmetry (technically bilateral still in bilateria) Flexible support structure along dorsal (back) side; made of cartilage (2) dorsal, hollow nerve cord. Fluid-filled, like spine (3) pharyngeal slits or clefts. Near pharynx (throat) function as gills for respiration (in aquatic environments) (4) post-anal tail. Tunicates just 1 hox cluster (a gene that calls for regulatory proteins) Derived traits (1) bone or cartilage vertebrae replaced notochord (2) 2+ hox clusters. Lead to increased genetic complexity more complex body plan. Jaw mouth (1) hinged jaw grasp and hold prey (2) 4 hox clusters allow for more complexity. Bone fish (1) bony skeleton made of calcium phosphate (2) first group with lungs (or related structures) Swim bladder these fish fill it with air and prevents them from sinking.
